diff --git a/.github/workflows/torsten_test.yml b/.github/workflows/torsten_test.yml
index aae43a2394..907c67cc65 100644
--- a/.github/workflows/torsten_test.yml
+++ b/.github/workflows/torsten_test.yml
@@ -76,25 +76,31 @@ jobs:
     - uses: actions/setup-python@v4
       with:
         python-version: '3.x'
-    - name: Set up R
-      uses: r-lib/actions/setup-r@v2
+    - uses: r-lib/actions/setup-r@v2
       with:
-        rtools-version: '43'
-    - name: Print g++ info
+        r-version: 4.1.3
+
+    - name: Set path for Rtools40
+      if: runner.os == 'Windows'
+      run: echo "C:/rtools40/usr/bin;C:/rtools40/mingw64/bin" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
+    - name: Install mingw32-make and check toolchain path
+      if: runner.os == 'Windows'
       run: |
+        pacman -Syu mingw-w64-x86_64-make --noconfirm
         g++ --version
         Get-Command g++ | Select-Object -ExpandProperty Definition
-    - name: Print mingw32-make info
-      shell: powershell
-      run: |
         mingw32-make --version
         Get-Command mingw32-make | Select-Object -ExpandProperty Definition
+      shell: powershell
+
     - name: Build Math libs
       shell: powershell
-      run: mingw32-make -f make/standalone math-libs
+      run: |
+        Add-Content make\local "O=1`n"
+        mingw32-make -f make/standalone math-libs -j2
     - name: Add TBB to PATH
       shell: powershell
-      run: echo "D:\a\math\math\lib\tbb" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+      run: echo "D:/a/math/math/lib/tbb" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
     - name: Add Torsten to PATH
       shell: powershell
       run: echo "D:/a/math/math/stan/math/torsten" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8